• Journal of Marine Life Science
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• v.7 no.1
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• pp.45-51
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• 2022

The profer salinity range for aquaculture of hybrid grouper (Epinephleus bruneus♀ × Epinephleus lanceolatus♂) were evaluated in terms of their survival, growth, feed intake and physiological responses after 30 days of exposure to different salinities (0 psu, 3 psu, 5 psu, 10 psu, 15 psu, 20 psu, 25 psu, 30 psu). Hybrid grouper all died at 0 psu salinity on the 4th day of exposure but all hybrid survived at a salinity of 5 psu or higher during the exposure period. Body length and weight increased above 5 psu salinity and the growth rate was the highest at 30 psu. Hybrid exposed to 3 psu did not eat the feed pellet. Feed intake did not show a significant difference between salinity 20 psu, 25 psu and 30 psu. Plasma osmolality of the juvenile hybrids exposed to different salinities was 341~368 mg Osmol/kg above 5 psu. The oxygen consumption rate was the highest at 30 psu with 163.6±22.3 mg O₂/kg fish/h. SOD, CAT and GSH-PX were significantly higher at 15 psu. Therefore, the critical salinity for survive of the juvenile hybrid was 5 psu, and the proper salinity for optimal culture was analyzed with 20~30 psu.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.684-689
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• 2017

We examined the possibility of developing an early monitoring system using the shell valve movement activity of Pacific oyster (Crassostrea gigas) for early detection of low salinity water in coastal areas. At salinity levels of 30 psu and 20 psu, SVMs were detected $7.32{\pm}3.21times/hr$ and $7.11{\pm}3.90times/hr$, respectively, The patterns and times of SVMs were not significantly different between the two experiment phases. However, at 10 psu and 5 psu, shell valves were observed to be permanently closed in all experiments. Under combined condition (Group 1: temperature $15^{\circ}C$ ${\times}$ salinity 15 psu), SVMs were observed from 20 psu to 30 psu over a 2 - 3 hr period, and then remained closed. In Group 2 (temperature $30^{\circ}C$ ${\times}$ salinity 15 psu), SVMs were observed, which indicated that the physiological condition of the oysters reached a critical point. Thus, it may be possible to utilize SVMs as an early warning signal for low salinity water.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.620-627
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• 2020

Oxygen consumption and blood physiology of olive flounder Paralichthys olivaceus (mean body weight 106.6±6.8 g, mean±SD) was investigated at salinities of 34.0 (control), 33.7, 33.3, 32.6, 31.3, 28.6, 23.1, 12.2 and 0.0 psu at 20.0℃, respectively. Stepwise salinity changes (34.0→33.7→33.3→32.6→31.3→28.6→23.1→12.2→0.0 psu) with an interval of 24 h for each salinity induced a significant (P<0.05) increase of oxygen consumption rate (OCR) in fish exposed from 31.3 to 0.0 psu compared to that of control fish. The maximum OCR was found in fish exposed to 23.1 psu, which was accompanied by 36.2% higher energy consumption than the control fish. Fish exposed to each salinity for 24 h induced a significant decrease of blood plasma Na⁺ in 0.0 psu and Cl^- in 12.2 and 0.0 psu (P<0.05), and increase of plasma glutamic oxaloacetic transaminase (GOT) in 0.0 psu compared to the control fish (P<0.05). The results of this experiment show that P. olivaceus exposed to concentrations below 31.3 psu requires more energy costs to adapt to salinity changes than 34.0 psu under our experimental conditions.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.39-48
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• 2017

This study was carried out to investigate the stress response of pacific abalone exposed to various water temperatures (4, 6, 8, and 10℃) and salinities (26, 30, and 34 psu) for 7 days, with the aim of finding optimum conditions for long-distance ocean transport of pacific abalone. At the end of the experiments, the survival rate was ranged from 98.7~100% at 8 and 10℃ but dropped to 25~55% at 4℃ in all salinity levels. The levels of SOD and glutathione in hemolymph were significantly higher at 4 and 6℃ than the control in all salinity groups, indicating that these temperatures induce severe stress in pacific abalone. It was found that THC was lowest at 6℃ in the 26 psu groups. The study showed that the hemocyte of pacific abalone populations mostly consisted of blast-like cells and hyalinocytes with the ratio of hyalinocytes being significantly lower at 4 and 6℃ than the other temperatures in the 26 psu groups. Percentages of apoptotic cells and necrotic cells were higher in the 26 psu group and 4 and 6℃ temperature groups. These results explicit that pacific abalone was exposed to greater stress at 26 psu and at 4 and 6℃ but experienced no significant higher stress at 30 and 34 psu and 8 and 10℃. It was therefore concluded that the optimum temperature and salinity for the long distance transport of pacific abalone range from 8~10℃ and 30~34 psu, respectively.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.283-289
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• 2011

This study investigated survival rate, osmorality, respiration, excretion and histological response with change of salinity in the abalone, Haliotis discus hannai at $24{\pm}1^{\circ}C$. Survival rate was 100% at 37.0 psu whereas all died after 6 days at 19.8 psu and within 24 hours at 12.8 psu, respectively. The 7-day median lethal limit (7day-$LS_{50}$) was 20.1-28.2 psu with confidence limits of 20.1-28.2 psu. Respiration rate in low salinity groups was lower than control group, but ammonia excretion rate was more increased in comparison to control group. Osmorality was acclimated within 1 hour at above of 26.8 psu but others could not acclimated at each experimental salinity. Histological observation of foot muscle showed hemolymph sinus distension, epidermal destruction and increased infiltration of phagocytes.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.363-370
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• 2014

We investigated the survival rate by water temperature and salinity, physiological rhythm and morphological change of live abalone to get to know optimum water temperature and salinity suitable for long-distance transportation of live abalone. At $8^{\circ}C$ and above, 96-100% of survival rate was shown at all experiment groups. At $6^{\circ}C$, 66% of abalones survived in normal seawater but they showed 0% of survival rate at $30{\pm}0.5psu$ and $26{\pm}0.5psu$ of salinity at the same water temperature. There was no significant difference of oxygen consumption rate for a week between the seawater and $30{\pm}0.5psu$. Also, a positive correlation was shown between salinity and water temperature and the oxygen consumption rate was slightly higher at $30{\pm}0.5psu$ than seawater. Thinned epithelial layers and expansion of lymph sinus were observed less than $30{\pm}0.5psu$ or below $6^{\circ}C$ of temperature. This result shows that the optimum level of water temperature and salinity is considered to be $6-8^{\circ}C$ and more than $30{\pm}0.5psu$ respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.1
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• pp.39-51
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• 2011

Acute toxicity test and behavioral change analysis of seawater acclimated Japanese medaka were conducted to identify the brine effects on fish by seawater desalination. 7 day acute toxicity test of brine revealed linear concentration-response relationship from 40.0~80.0 psu treatment groups. There was no significant brine effect for 30-40 psu groups and mass mortality was observed from >50 psu exposure (7-day $LC_{50}$=51.4 psu). Images from the real time camera system were analyzed to observe the changes in behavioral patterns of medaka exposed to various salinity. 40.0 and 50.0 psu exposed groups were stabilized in behavioral patterns after 3.1 and 4.6 hours, respectively and 60.0 psu group showed sharp increase in activity during first 12 hours and 50% mortality thereafter. Similar patterns were observed to 70 and 80 psu groups and both experimental groups showed 100% mortality within 12 hours. Acute toxicity test and behavioral patterns showed very similar toxicity results which revealed the increases in mortality and behavioral activities from 50.0 psu. This critical salinity for fish impacts must be implemented to brine discharge strategy by seawater desalination into the coastal area. Also, we recommend that real time camera monitoring system must be a useful tool for early warning of fish toxicity for other applications. This research was funded by Ministry of Land, Transport and Maritime Affairs, Korea.

• Fisheries and Aquatic Sciences
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• v.7 no.1
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• pp.39-45
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• 2004

Six demographic parameters including life span (LS), maturation time (MT), net reproduction rate (Ro), mean generation length (G), innate capacity for increase $(r_m)$ and finite rate of increase $(\gamma)$ were estimated in the rotifer (Brachionus rotundiformis) cultured at three salinities of 5, 20 and 34 PSU and under a constant temperature of $28^{\circ}C$. The maximum life spans at salinities of 5, 20 and 34 PSU were 17, 12 and 13 days, respectively. The shortest maturation time (24 hr) was recorded at 5 PSU, and the rotifer at 20 PSU showed a most delayed maturation (192 hr). The maximum reproduction rate was 42 offspring per female in rotifer cultured at 5 PSU, while the longest generation length (8 days) was observed at 20 PSU. Maximum and minimum values of $r_m$ (1.56 and 0.46 individual per day) and $(\gamma)$ (6.67 and 1.70 individuals per day) were calculated at 5 and 34 PSU, respectively. Salinity also showed strong effect on correlation of the demographic traits examined. ANOVA revealed significant differences (P<0.05) between demographic parameters of the rotifer at the three salinity condition. Considering the higher values of life span, innate capacity and finite rate of increase, and shortest maturation time at 5 PSU, the rotifer we examined had a higher reproductive potential and longer life span at 5 PSU rather than at 20 or 34 PSU.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.225-232
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• 2013

This study looked into recovery rate and histological changes in the gills of juvenile abalone Haliotis discus hannai by exposure time (3, 6, 12, 24 and 48 h) of different water temperatures (15, 20 and $25^{\circ}C$) and salinities (30, 25, 20 and 15 psu) to understand reasons for the death of abalone exposed by low salinity water. In each water temperature, abalone spats that were exposed to low salinity water (less than 20 psu) for over 6 hours showed decrease in survival rate during recovery and those were exposed at the salinity of 15 psu for more than 24 hours all died. Histological observation showed expansion or damage of gills of the species which were exposed at less than 20 psu for over 6 hours. In case of abalones exposed at the salinity of 15 psu for over 24 hours, most gill tissues were destroyed. This result was glaringly obvious at a higher water temperature, lower salinity and longer exposure time. Accordingly, suffocation caused by damage of gills considered one of direct causes of the death.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.6
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• pp.1360-1365
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• 2013

Juvenile sea cucumber, Apostichopus japonicus(wet weight $1.0{\pm}0.2g$, n=250) acclimated to environmental conditions($17^{\circ}C$, 33 psu) during 4 weeks for observation of survival and structural variation of integumentary system according to various salinity concentration. After that, it was exposed 0, 5, 10, 15, 20, 25, 30, 35, 40 psu in 96h, and recovered during 7 days. In this results, The 96-h lethal concentration(LC50) for sea cucumber was a salinity of 21.05 psu. Integumentary system of the sea cucumber exposed to below the salinity of 20 psu mainly observed thickness reduction of epidermal layer, nucleus condensation of epithelial cells, decreased of mucous cells and loose arrangement of connective tissue in dermal layer. Integumentary system of the sea cucumber exposed a salinity of 40 psu mainly observed nucleus hypertrophy of epithelial cells, increase of mucous cells and tight arrangement of connective tissue in dermal layer. Also, observed secretory cells showing the alcian blue(pH 2.5) positive. During 96-h exposure, this cells decreased after increase below the salinity of 20 psu but increased in the salinity of 40 psu compared with 25-35 psu.